Bleacing linen yarns and tissues.

The Textile Mercury, 12.3.1892

Mahien's process consists in mixing benzine with the solutions of carbonate of soda used in the different bleaching operations, or with the baths of chloride of lime or other bleaching chlorides. This application of benzine in the yes[?] has the effect of dissolving and removing the vegetable colouring and resinous substances contained in the textile matters. Taking, for instance, 1,000 kilos. linen to bleach, the way of operating after this method is as follows viz.:
In a sheet-iron kier or other boiler containing 200 litres water, 50 kilos. soda, "preferably Solvay soda" is heated for fifteen minutes at about 100°C., when 1¼-1½ litres benzine is added and beating continued for ten minutes, the mixing operation taking up 25 minutes in all. After standing for ten minutes the mixture is let out into another kier placed under the first, containing 5,000 litres hotwater and 12½ kilos. lime. This lime-water bath is prepared one hour in advance and heated; to 90-100°C. This new mixture is heated for another hour, and then left to stand for twelve hours before using it. The 1,000 kilos. linen being placed into a proper tub, and the prepared lye run in, it is boiled for three hours under 22½ lb. pressure, instead of five hours as usual. This process applies to the whole course of operations, which are more or less often repeated according to the degree of bleaching required, as the following scheme of bleaching operations shows:-
1. Benzine lye as above indicated.
2. Rinsing in running water.
3. Chloride of lime bath.
4. Rinsing.
5. Neutralisation of the chlorine.
6. Rinsing.
7. Grass bleach.

Benzine is also added to the chlorine bath, thus:
Mix 8 kilos. benzine with 60 kilos. Solvay soda, and let it boil up; run this mixture into a cistern containing 4,000 litres solution of lime, or about 4% benzine. Then the chlorine baths are prepared, as stated, to the required strength, and the yarns or linens are laid down in them for a suitable period. This process renders all the ordinary bleaching operations more active and at the same time shortens them, maintains the fibres at their original strength, and yields a considerable saving in steam and chemicals. Of course, exceptional care must be taken m working with such inflammable materials as benzine.